1. Field of the Invention
The present invention relates to an organic light-emitting compound, and an organic light-emitting device using the organic light-emitting compound, and more particularly, to an organic light-emitting compound that has excellent electrical characteristics, thermal stability and photochemical stability, and provides a low turn-on voltage and excellent color purity characteristics when used in an organic light-emitting device, and an organic light-emitting device with an organic layer containing the organic light-emitting compound.
2. Description of the Related Art
Light-emitting diodes, which are self-emissive devices, have the advantages of a large viewing angle, a high contrast, and a short response time. Light-emitting diodes can be classified into inorganic light-emitting diodes using an inorganic compound in their emitting layer and organic light-emitting diodes (OLEDs) using an organic compound in their emitting layer. OLEDs have higher brightness, lower driving voltage, and shorter response time than inorganic light-emitting diodes and can achieve full color display. Due to these advantages of OLEDs, much research into OLEDs has been performed.
OLEDs have a stacked structure including an anode, an organic light-emitting layer, and a cathode. OLEDs can have various structures including, for example, a stack of an anode, a hole injecting layer, a hole transporting layer, an emitting layer, an electron transporting layer, an electron injecting layer, and a cathode, a stack of an anode, a hole injecting layer, a hole transporting layer, an emitting layer, a hole blocking layer, an electron transporting layer, an electron injecting layer, and a cathode, etc.
Materials used to form an organic layer of an organic light-emitting device can be classified into either materials suitable for vacuum deposition or materials suitable for liquid coating according to a method used to form the organic layer. Materials suitable for vacuum deposition may be low-molecular weight materials having a vapor pressure of 10−6 torr or greater at 500° C. or lower. Materials suitable for liquid coating should be highly soluble in a solvent so as to be used in a liquid form and have an aromatic or complex ring.
When an organic light-emitting device is manufactured using vacuum deposition, due to the use of a vacuum system, the manufacturing costs increase. Furthermore, when a shadow mask is used to form pixels for full-color display, the resolution of the pixels is not sufficiently high. Meanwhile, when a liquid coating method, such as inkjet printing, screen printing, spin coating, etc., is used, the manufacturing processes are easy, and a higher resolution than when using a shadow mask can be obtained.
However, materials which are compatible with liquid coating, and in particular, blue luminescent materials, are inferior to materials which are compatible with vacuum deposition, in terms of thermal stability, color purity, etc. However, even when a material, which is compatible with liquid coating, with excellent performance is formed as an organic layer, the material is crystallized with a crystal size that can scatter visible light, which may cause white turbidity and leads to pin holes in the organic layer, thereby causing deterioration in the device.
Japanese Patent Laid-open No. 1999-003782 discloses anthracene substituted with two naphthyl groups as a compound that can be used in an emitting layer or a hole injecting layer. However, the compound has poor solubility in a solvent, and the characteristics of an organic light-emitting device containing the compound are not satisfactory.
Thus, there still is a need to develop an organic light-emitting device with improvements in turn-on voltage, luminance, efficiency and color purity characteristics using a blue luminescent material that has a high thermal stability and can form an organic layer with excellent properties.